Makes you wonder if it would just be easier to drop IE and support Mozilla. Its great already, and would make both MS's life easier as well as Mozilla if they had the support. Now, Im not one of those Open Source freaks that preaches OSS everywhere.
If Mozilla was closed, I would still recommend it. At this point, IE is very far behind the game, and playing catch-up could be costly to MS. Programmers that could be better used elsewhere.